This invention is related to wiring devices used on branch wiring circuits to deliver electrical power. More particularly, this invention is related to wiring devices, such as power strips, in which multiple branch circuits can be balanced by reconfiguring the wiring device instead of rewiring a circuit protection device or a service entrance panel associated with the wiring device.
FIG. 11 shows a conventional power strip 100 including multiple receptacle outlets 102 that are hardwired to wires in a power cable 104 that connects the power strip 100 to a source of electrical power. The power strip 100 includes receptacle outlets 102 hardwired to a single line conductor. Different versions of the power strip 100 can employ different line conductors connectable to different circuits in an AMPINNERGY power distribution system such as that shown in U.S. Pat. No. 5,073,120, incorporated herein by reference. If a problem, such as an overload condition or power spikes, exists on one of the branch circuits of which a particular line conductor is a part, then additional electrical appliances or electronic components cannot be attached to unused outlets on that branch. Thus, not all receptacle outlets may be available, and when a new appliance is connected to a branch circuit, other appliances may have to be disconnected or an additional power strip, employing a different line conductor may have to be used. In facilities, such as retail display counters, laboratories, classrooms, hospitals or other environments in which repeated or rapid changeovers are necessary, there may not be enough outlets to service all of the devices at that location, even though some branch circuits might be underutilized.
For conventional installations it is necessary to reconfigure the branches at the service entrance or rewire a facility. This operation requires a trained service technician or electrical or wiring consultant who may not be readily available. For instance, in a retail outlet demonstration display area electrical appliances or electronic devices must be connected to existing branch circuits via a wiring device or power strip located in a specific area. When the display area is reconfigured it is often necessary for an electrician to rewire the display area. Often the electrician is not familiar with the layout of the wiring of the facility or that layout is not adequately documented. Even though the branch circuits are identified at the service entrance or circuit protection panel, the physical location of these branch circuits and the outlets or power strips attached thereto may not be easily ascertainable because of previous relocation of display areas. Similar problems can exist in other facilities, such as laboratories or other facilities in which numerous electrical and electronic devices are repeatedly rearranged.
The AMPINNERGY modular power distribution system is one alternative for simplifying installation and rearrangement of electrical power systems. AMPINNERGY is a trademark of Tyco Electronics Corporation. This system is used in modular office systems and in raised floor systems. Electrical power in those systems is distributed through sheathed cables to junction blocks that are mounted in modular wall panel raceways of the type commonly used in cubicle walls. The cable assemblies are available as eight wire systems with four line conductors and five wire systems with three line conductors. The junction blocks can be mounted in raceways in the base of the modular walls by brackets. Connectors on the sheathed cable assemblies are mated to the ends of these junction blocks. Duplex receptacle outlets can be mated with the junction blocks on opposite faces so that equipment can be plugged into the duplex receptacles on both sides of the wall panel. After the duplex receptacle outlets have been mated to the junction boxes, raceway covers are mounted in front of the duplex receptacle modules. These covers have openings to allow access to the duplex receptacle sockets, but the duplex receptacle outlets must be mated to the junction boxes before the covers are installed. Versions of the duplex receptacles can be connected to any one of the line conductors in the cable assemblies so that a duplex receptacle can be connected to a predetermined branch circuit. The individual components of this modular power distribution system include many features, such as multiple wires in cable assemblies and receptacle sites on opposite sides so that the components can be assembled in a wide variety of configurations to meet the need of a specific work space. Modular power distribution systems of this type are also suitable for use in raised access floor systems and on power poles.
An important advantage of the AMPINNERGY modular power distribution system is that the components of the system can be physically moved when space in which they are used is rearranged. Thus when modular wall panels are moved or when access floor outlets are physically rearranged, the cable assemblies can also be physically moved because they are not permanently fixed to the building structure. Although the components of this prior art modular power distribution system can be physically rearranged, the electrical configuration or layout of the branch circuits are not changed as part of this physical reconfiguration. The breaker panel or circuit protection device layout is originally configured by a trained consultant or electrician. The branch circuit configuration defined at the circuit protection device remains the same, even though the physical position of the outlets attached to the modular wall panels or access floor stations may change. To electrically reconfigure modular power distribution systems of this type a trained consultant or electrician would normally reconfigure the branch circuits at the circuit protection device.
Commercially available modular electrical power distribution systems of this type are flexible and facilitate rearrangement of office space, computer facilities, light manufacturing sites and similar commercial and industrial space. However, conventional installations do not address situations in which the types and numbers of electrical appliances or electronic devices that are attached to the branch circuits are frequently changed. For instance in a retail facility, display areas and the demonstration appliances connected in any one area, are changed so frequently that it is not practical to change either the physical arrangement of the major wiring components or the branch circuit layout each time a retail display is modified. When more electrical appliances are attached to a branch circuit available in a retail display, the branch circuit may be overloaded or transients and spikes may be occur that could adversely affect the performance of other electronic components attached to that branch. Thus the branch circuits available in a particular location may limit the configuration of appliances that can be displayed in a given retail display area. Sales or maintenance personnel who typically reconfigure the display area typically do not have proper qualifications to reconfigure the electrical layout to meet new, and perhaps transient, requirements, and it is not practical to employ electricians to continuously make such changes. Similar problems can arise in laboratories, light manufacturing workspaces and in other facilities where frequent changeovers are common.
The instant invention provides added flexibility in situations requiring rapid changeover of the branch circuits available at a specific site. With this invention, personnel, other than electricians or trained wiring consultants, can reconfigure branch circuits available at a particular location by simply substituting a receptacle outlet connectable to a different branch circuit. Different versions of receptacle outlets are available so that an installed receptacle outlet connected to an excessively loaded branch circuit can be replaced by a different receptacle outlet that is attachable to a different line conductor. If the new branch is also overloaded, a third receptacle outlet attached to a third line conductor, and therefore a third branch circuit, can be installed. Thus the flexibility of an existing wiring layout can be greatly enhanced.
Thus according to one aspect of this invention, a load balancing power strip for distributing electrical power includes a plurality of separate line conductors. A plurality of tap sockets are located on the power strip. A plurality of receptacles, such as duplex receptacle outlets, are matable with the tap sockets. Each tap socket includes a plurality of line contacts, each separate line contact being commoned to one of the line conductors. Each receptacle includes a terminal matable with one of the line contacts. Receptacles having terminals in different positions are attachable to each tap socket so that, at each tap socket, a receptacle can be connected to any one of the line conductors. The receptacles at each tap socket are replaceable to balance loads on the separate line conductors in the power strip.
According to another aspect, a wiring device, such as a power strip, for distributing electrical power at multiple receptacle outlets includes a tap socket assembly including a plurality of individual tap sockets. An enclosure assembly with multiple openings houses the tap socket assembly that is mounted in the enclosure assembly with individual tap sockets aligned with individual openings in the enclosure assembly. Receptacle outlets are connectable to the individual tap sockets. The receptacle outlets extend through the individual openings by a distance sufficient to permit insertion and removal through the individual openings to permit connection to and disconnection from the corresponding tap sockets.
An electrical wiring assembly of this type would be suitable for use in a retail display panel to balance loads on branch circuits providing electrical power to sample electrical components on display in a retail establishment. This electrical wiring assembly would include a tap socket assembly including bus bars for carrying electrical current. The bus bars would be located in a tap socket housing. The tap socket assembly would include multiple tap sockets. Each tap socket would have electrical contacts on the bus bars aligned with apertures in the tap socket housing. Each electrical wiring assembly also includes an end connector on at least one end. A cable assembly including multiple wires and a connector could be attached to the end connector. The cable assembly would connect the bus bars and the wires to an electrical service panel to form multiple branch circuits accessible in the tap socket assembly. A hanger assembly could be attached to the tap socket assembly. The tap socket assembly would be mounted on the retail display panel by the hanger assembly. The hanger assembly also would have openings aligned with the tap sockets on the tap socket assembly to provide access to the tap sockets. Receptacle outlets of at least a first type and a second type would also be used. The first type of receptacle outlet could be attached to a first bus bar at one or more of the tap sockets and the second type of receptacle outlet could be attached to a second bus bar at one or more of the remaining tap sockets. The first and second types of receptacle outlets are interchangeable and replaceable so that loads on the first and second bus bars can be balanced by substituting one type of receptacle outlet for another type of receptacle outlet. The hanger assembly openings provide access through which the receptacle outlets can be inserted and removed so that loads on different branch circuits can be balanced by changing the type of receptacle outlet in the retail display area without rewiring the branch circuits at the electrical service panel.